Candling and in ovo injection devices and techniques are well known in the art. For example, injection devices are known that inject treatment substances, such as vaccines, antibiotics or vitamins, directly into eggs, in order to limit the mortality rate or increase embryo growth. Such devices conventionally comprise an injection head which comprises a plurality of vertically moveable injectors above a routing conveyor of eggs to be treated, the eggs being conventionally positioned in cells of incubation trays. However, prior to the instant disclosure, no group has disclosed the automated delivery of substances to specific structures or regions of a developing avian embryo.